Cellulosic materials internally sized with low molecular weight copolymers of alpha, beta-ethylenically unsaturated hydrophobic monomers and ammoniated carboxylic acid comonomers

ABSTRACT

Cellulosic materials such as paper are internally sized by treating fibers of the cellulosic material, e.g., paper pulp, with a low molecular weight copolymer of an Alpha , Beta ethylenically unsaturated hydrophobic monomer and an ammoniated, Alpha , Beta -ethylenically unsaturated carboxylic acid and a cationic retention aid. Internal sizing of the cellulosic material by this method can be carried out under acidic, neutral or basic conditions.

United States Patent Vaughn et a1.

1 1 CELLULOSIC MATERIALS INTERNALLY SIZED WITH LOW MOLECULAR WEIGHT COPOLYMERS OF ALPHA, BETA-ETHYLENICALLY UNSATURATED HYDROPHOBIC MONOMERS AND AMMONIATED CARBOXYLIC ACID COMONOMERS Inventors: Walter Lee Vaughn, Lake Jackson;

Robert James Beam, Angleton, both of Tex.

The Dow Chemical Company, Midland, Mich.

Filed: Feb. 1, 1974 Appl. No.: 438,914

Assignee:

US. Cl. 260/174 ST, 162/164, 162/168, 162/169,162/175,162/185, 260/174 CL Int. Cl C08g 45/18 Field of Search 260/174 ST, 17.4 CL; 162/168,164, 175,185,169

References Cited UNlTED STATES PATENTS 10/1966 Yoshii et a1 162/168 OTHER PUBLICATIONS Union Carbide Brochure, F-42958," Products for Paper, PC4300, Analkal: Dispersible Ethylene Copolymer, printed 10/70; pp. l2, 4l2, and 14.

Primary E.\'aminer-Morris Liebman Assistant E.raminerEdward Woodberry Attorney, Agent, or FirmRichard G. Waterman; Michael S. Jenkins [57] ABSTRACT Cellulosic materials such as paper are internally sized by treating fibers of the cellulosic material, e.g., paper pulp, with a low molecular weight copolymer of an a,B-ethylenically unsaturated hydrophobic monomer and an ammoniated, a, B-ethylenically unsaturated carboxylic acid and a cationic retention aid. Internal sizing of the cellulosic material by this method can be carried out under acidic, neutral or basic conditions.

21 Claims, No Drawings CELLULOSIC MATERIALS INTERNALLY SIZED WITH LOW MOLECULAR WEIGHT COPOLYMERS OF ALPHA, BETA-ETI-IYLENICALLY UNSATURATED HYDROPI-IOBIC MONOMERS AND AMMONIATED CARBOXYLIC ACID COMONOMERS BACKGROUND OF THE INVENTION This invention relates to internal sizing of cellulosic material over the complete range of pH conditions which are normally encountered in the cellulosic manufacturing arts.

Cellulosic materials such as paper and paperboard, are often sized with various materials with the purpose of increasing their resistance to water penetration as well as to penetration by other types of aqueous solutions. These materials are referred to as sizes or sizing agents and they may be introduced during the actual manufacture ofthe cellulosic material, e.g., paper making operation, wherein the process is known as internal sizing, often called beater sizing, wet end sizing or engine sizing. Surface sizing cellulosic materials by applying sizing agent to fabricated sheet or web is also well known; but is usually considered to be substantially different from internal sizing.

The basis of present internal sizing methods is the intimate coating of the individual fibers of the cellulosic material with a material which is insoluble in most materials and is repellant to water. For example, in manufacture of paper, the substance originally and still most widely used for this purpose is rosin or fatty acid. In order to insure the most intimate contact between the rosin and the pulp fiber, the former is added in either the dissolved state or as a finely dispersed emulsion. It is followed by a precipitating agent,usually aluminum sulfate, known to the paper maker as alum. The alum coagulates the rosin, i.e., throws it out of solution or emulsion as a gelatinous precipitate. Since the rosin or emulsion is first mixed thoroughly with the pulp in the beater, the precipitate has a maximum chance of adhering to and being subsequently retained by the pulp. When the pulp is made into paper, the rosin in contact with the pulp adheres to the pulp as small particles, e.g., particles having diameters of one micron or less. The paper having the small particles of rosin adhered to the fibers exhibits the desired strength and ink and water resistance.

In addition to rosins, various water-repellant or hydrophobic materials have been utilized as internal sizing agents. These include fortified rosin, mixtures or rosins with waxes, wax emulsions, ketone dimer emulsions, fluorocarbons, fatty acid complexes of chromium or aluminum chlorides, long chain thermoplastic copolymers, as well as thermosetting condensation-type resins. Although all of these materials are effective under certain conditions, their use is nonetheless subject to one or more limitations.

For example, in the case of rosin, it is only useful as sizing agent in acidic solutions and therefore cannot be used for the sizing of neutral or alkaline pulps. Rosin is inoperable with the latter since it must ordinarily be used in combination with alum, or an acidic aluminum ion donor which is present for the purpose of precipitating and setting the metal rosinate onto the fibers. The use of alum for this purpose is, however, precluded under neutral or alkaline stock conditions. This is a definite disadvantage in paper making since paper produced from neutral or alkaline pulp has been found to have higher strength, greater stability and superior aging characteristics in comparison with paper prepared from acidic pulp. Also, the internal use of alkaline pigments such as calcium carbonate is precluded. This limitation also applies to most wax emulsions which cannot be used on the alkaline side since they are usually combined with small quantities of alum for the purpose of breaking the emulsions. On the other hand, it may be noted that certain sizing agents will not tolerate acidic conditions. In addition to the above described pH limitations, the water resistance or water holdout which is obtainable with many of the heretofore employed sizing agents is often inadequate for many applications which require paper or paperboard displaying an exceptionally high degree of waterresistance. Some sizing agents provide complete water repellancy as opposed to the desired limited amount of water-resistance. Many sizing agents have been found to be incompatible with pigments, fillers or other ingredients which are often added to the paper. A further disadvantage of some sizing agents is that a considerable degree of heat curing is required in order to develop full effectiveness.

For these and other reasons, it would be highly desirable to provide an internal sizing agent which can be effectively employed under acidic, neutral or alkaline conditions and which can be cured to a size having the desired limited water resistance under normal drying conditions used in the early stages of manufacturing paper and other cellulosic materials.

SUMMARY OF THE INVENTION In the present invention, paper and other cellulosic materials are internally sized under pH conditions ranging from moderately acidic through strongly alkaline by an improved internal sizing method. In this improved method for internally sizing the cellulosic material wherein an internal sizing agent is applied to the fibers of the cellulosic material, the improvement comprises the use of a low molecular weight copolymer of an afi-ethylenically unsaturated hydrophobic monomer and an ammoniated a,B-ethylenically unsaturated carboxylic acid as an internal sizing agent and a cationic retention aid. In another aspect, this invention is an internal sizing composition for a cellulosic material comprising a sizing amount of the aforementioned copolymer and an amount of a cationic retention aid which is effective to retain the copolymer on the cellulosic material. In a further aspect, this invention is a cellulosic material internally sized with the aforementioned composition. The resultant internally sized cellulosic material displays a very desirable degree of water-resistance along with resistance of acidic and alkaline solutions. Of prime importance is the fact that the successful use of the aforementioned copolymers as sizing agents is not restricted to acidic pH which thus allows utilization of such sizing agents in the treatment of neutral and alkaline pulp as well as acidic pulp. Furthermore, it is found that only mild drying and curing conditions are needed to develop the full sizing value of such internal sizing agents.

DETAILED DESCRIPTION OF THE INVENTION For the purposes of this invention, the term cellulosie material is meant to include paper, paper board and other fibrous, sheet-like or molded masses derived from wood, wood pulp, or cotton or other sources of cellulosic fibers. This term also includes sheet-like or molded masses prepared from combination of cellulosic materials and non-cellulosic materials such as polyamides, polyesters, polyacrylic acid resin fibers and mineral fibers such as asbestos, glass and the like.

By the term internal-sizing is meant a method of sizing in which the cellulosic material inraw form, e.g., fibrous stock such as paper pulp, is contacted with the sizing agent under conditions effective to'size the cellulosic material, i.e., deposit the sizing agent on the fibers and cure it to full sizing effectiveness. Accordingly, it is understood that the term internal sizing is generic, and therefore includes such terms as beater-sizing, engine-sizing, internal wet end sizing and the like.

The internal sizing agents suitably employed in the practice of this invention are copolymers of a,/3-ethylenically unsaturated hydrophobic monomer and ammoniated a,B-ethylenically unsaturated carboxylic acid, i.e., a,B-ethylenically unsaturated carboxylic acid in the ammonium salt form. Generally, such copolymers are water-dispersible, semi-solid or solid materials. The molecular weights of such copolymers, measured as number average molecular weight by embulliometry, are suitably in the range generally from about 1,000 to about 10,000, preferably from about 3,000 to about 8,000 and especially from about 4,000 to about 7,000. Suitable copolymers have melt flow viscosities in the range generally from about 0.5 decigram/minute to about 50 decigrams/minute as measured using the procedure of ASTM Dl238-65T(B) except that the orifice of the extrusion plastometer is 0.020 inch. Preferably the copolymers are film-forming at temperatures used in the sizing operations. By water-dispersible is meant a material which can exist in the form of a stable aqueous colloidal dispersion in the absence of a surface active agent. In addition, the copolymers in the form of aqueous dispersion preferably form films under ambient conditions which films dry to form water-insoluble coatings. By a,B-ethylenically unsaturated hydrophobic monomer is meant any water-immiscible monomer containing a terminal double bond capable of polymerization under normal conditions of addition polymerization to form a water-insoluble homopolymer having a polyethylenic backbone. By a,B-ethylenically unsaturated carboxylic acid" is meant an a,B-ethylenically unsaturated carboxylic acid which is capable of addition copolymerization through the ethylenically unsaturated group with the a,/3-ethylenically unsaturated hydrophobic monomer. By ammoniated a,B-ethylenically unsaturated carboxylic acid is meant that in the copolymer the carboxylic acid groups are neutralized with ammonia.

Preferably, the internal sizing agent is a normally solid, waterand alkali-insoluble thermoplastic addition copolymer in the form of a fluid aqueous colloidal dispersion. The occurrence of ammoniated acid groups in the polymer should be general throughout the macromolecules thereof so that each macromolecule contains a minimumm number of active salt groups sufficient to render the polymer water-dispersible as defined hereinbefore. The maximum number of ammoniated acid groups which may be present in the macromolecules is fixed by the requirement that the molecule be substantially water-insoluble. Generally speaking, such copolymers contain from about 6 to about weight percent of ammoniated acid comonomer, with preferred copolymers containing from about 10 to about 20 weight percent of ammoniated acid comonomer and especially preferred copolymers containing from about 15 to about 18 weight percent.

Exemplary preferred copolymers are the random copolymer products of copolymerization of mixtures of one or more polymerizable ethylenically unsaturated carboxylic acids having 3 to 8 carbon atoms inclusive of anhydrides and alkyl half esters of ethylenically unsaturated acids such as acrylic acid, methacrylic acid, maleic acid and anhydride, itaconic acid, fumaric acid, crotonic acid and citraconic acid and anhydride, methyl hydrogen maleate, ethyl hydrogen maleate, and one or more a,B-ethylenically unsaturated hydrocarbon monomers such as the aliphatic a-olefin monomers, e.g., ethylene, propylene, butene-l and isobutene; conjugated dienes, e.g., butadiene and isoprene; and monovinylidene aromatic carbocyclic monomers, e.g., styrene, a-methylstyrene, toluene, and tbutylstyrene. In addition, other ethylenically unsaturated hydrophobic monomers which are not entirely hydrocarbon are copolymerized with the aforementioned acid comonomers. Examples of such suitable monomers which are not entirely hydrocarbon include esters of a,B-ethylenically unsaturated carboxylic acids such as ethyl acrylate, methyl methacrylate, ethyl methacrylate, methyl acrylate, isobutyl acrylate, and methyl fumarate; unsaturated esters of non-polymerizable carboxylic acids such as vinyl acetate, vinyl propionate, and vinyl benzoate; vinyl halides such as vinyl and vinylidene chloride; vinyl ethers; a,,8-ethylenically unsaturated amides and nitriles such as acrylamide, acrylonitrile, methacrylonitrile and fumaronitrile. it is understood that the aforementioned suitable hydrophobic monomers may be copolymerized with preferred hy drocarbon monomer and the acid comonomer in proportions such that a waterand alkali-insoluble polymer is provided. Preferred copolymers include copolymers from about to about weight percent of ethylene, from about 10 to about 20 weight percent of one or more ammoniated ethylenically unsaturated acids such as acrylic acid and methacrylic acid and from 0 to about 20 weight percent of suitable ethylenically unsaturated hydrophobic monomer as described hereinbefore such as acrylonitrile, ethyl acrylate and vinyl acetate.

Other copolymers which are suitable are made from pre-formed, non-acid polymers by subsequent chemical reactions carried out thereon. For example, the carboxylic acid group may be supplied by grafting a monomer such as acrylic acid or maleic acid onto a polymer substrate such as polyethylene. Additionally, copolymers containing carboxylic anhydride, ester, amide, acylhalide and nitrile groups can be hydrolyzed to carboxylic acid groups which can then be neutralized to form the ammoniated carboxylic acid.

It is further understood that the a,,8-ethylenically unsaturated carboxylic acid in ammonium salt form may be copolymerized with the hydrophobic monomer in order to prepare a suitable copolymer.

Specified procedures and means for making the polymers are known to the art as exemplified by U.S. Pat. No. 3,520,861 to Thomson et a1. and U.S. Pat. No. 3,426,363 to Helin. The low molecular weight copolymers are advantageously prepared by employing a telogen such as propylene in the practice of the process of U.S. Pat. No. 3,520,861. In instances wherein the acid copolymer is obtained in mass form, the copolymer may be converted to aqueous colloidal dispersion in accordance with the methods of U.S. Pat. No. 3,389,109 to Harmon, et al. which is subsequently concentrated and ammoniated by the method described in US. Pat. No. 3,644,258 to Moore et al. Generally methods of producing the aqueous colloidal dispersion ofa copolymer which require the use of little or not emulsifier or other surface active agents are preferred. Preferably, the aqueous colloidal dispersion of copolymer has a polymer solids content from about 5 to about 60 weight percent and sufficient stabilizing ammonia to give the dispersion a pH of at least about 7.5. High solids dispersions are suitably prepared from lower solids dispersions by the method disclosed in the aforementioned patent to Moore et al.

In order to obtain a degree of sizing which is useful in manufacture of sized paper, it is necessary to utilize the copolymer sizing agent of the present invention in conjunction with any conventional retention aid which possesses cationic characteristics although it may not bear a cationic charge, herein called a cationic retention aid. These retention aids are useful as co-additives which enhance the retention of the copolymer sizing agent and which bring the copolymer sizing agent in closer proximity to the fibers of the cellulosic materials during the sizing operation.

Among the retention aids which may be employed are long chain fatty amines; polyamines such as polyalkylene polyamines including polyethylenimine and its derivatives; polyacrylamide; copolymers of ethylenimine with various monomers such as diethyl aminoethyl methacrylate; chromic sulfate; sodium alumate; aluminum sulfates (alum); animal glue; resins such as the reaction products of dibasic carboxylic acids, polyalkylene polyamines and epihalohydrins; reaction products of epihalohydrin and ammonia such as disclosed in U.S. Pat. No. 3,655,506 to Baggett including the reaction products of epihalohydrin and aliphatic polyamine having at least two amine hydrogens per molecule and reaction product of epihalohydrin and a mixture of ammonia and the polyamine as said reaction products are further described in US. Pat. No. 3,655,506 to Baggett which is hereby incorporated by reference in its entirety; polyamide polymers and copolymers such as polyamidepichlorohydrin resins, vegetable gums, starch and modified starches such as oxidized starch and hydroxyethylated starches. Also of interest for use as retention aids are various cationic starch derivatives including primary, secondary, tertiary or quaternary amines, starch derivatives and other cationic nitrogen substituted starch derivatives, as well as cationic sulfonium and phosphonium starch derivatives. Preferred retention aids are the water-dispersible reaction products of epihalohydrin and ammonia and- /or polyamine, including the reaction products of epihalohydrin and polyamine or mixture of polyamine and ammonia. Such reaction products have peak molecular weights as determined by gel permeation chromatography in the range from about 1000 to about 80,000, and comprise from about 0.9 to about 2.1 moles of epihalohydrin per mole of amine, i.e., ammonia, aliphatic polyamine or mixture of ammonia and polyamine.

In the internal sizing of paper and other cellulosic materials using the above-described copolymers as internal sizing agents, a number of variations and techniques may be employed. It is critical however, that all of the techniques employed achieve uniform dispersal of the sizing agent throughout the cellulosic fiber during internal sizing. Uniform dispersal may be obtained by adding the ammoniated copolymer sizing agent in a fully dispersed form such as an aqueous colloidal dispersion. Any of the aforementioned retention aids may be added to the cellulosic fiber stock, e.g., the pulp slurry, either prior to, along with or after the addition of the ammoniated copolymer sizing agent. In order to achieve maximum distribution, it is preferable that the retention aid be added either subsequent to or simultaneously with the sizing agent.

Although order of addition of the ammoniated copolymer sizing agent and the retention aid is not critical, it is usually desirable, particularly when the retention aid is highly cationic or is a flocculant for the copolymer sizing agent, to add the copolymer sizing agent to the fiber stock prior to addition of the retention aid, simultaneously therewith or shortly thereafter, e.g., usually within 30 minutes. Preferably the copolymer sizing agent is added to the fiber stock slurry prior to addition of the retention aid. Whichever technique is chosen for the addition of the ammoniated copolymer and cationic retention aid to the fiber stock, care must be taken to avoid contact of the ammoniated copolymer and the retention aid prior to contacting the fiber stock.

The actual addition to the cellulosic material fiber of either the retention aid or the sizing agent may take place at any point in the cellulosic material manufacturing process prior to the ultimate conversion of wetfibrous material into web, sheet or molded article. Thus, for example, in paper manufacture, the sizing agent may be added to the pulp while the latter is in the head box, beater, hydropulper or stock chest.

in order to obtain good internal sizing, it is desirable that the ammoniated copolymer sizing agents be uniformly dispersed throughout the fiber in as small a particle size as it is possible to obtain. One method for providing such uniform dispersions is to disperse the sizing agent in aqueous media prior to its addition to stock using, for example, a method as described hereinbefore. While it is generally desirable to use the ammoniated copolymer sizing agent in aqueous colloidal dispersion which is free of emulsifiers and surface active agents, such agents can be suitably employed in the practice of the invention provided that such agents are fugitive during sizing or otherwise do not impair the effectiveness of the copolymer sizing agent.

The sizing agents of this invention are most successfully utilized for the sizing of paper prepared from all types of both cellulosic and combination of cellulosic with non-cellulosic fibers. The cellulosic fibers which may most advantageously be used include the bleached and unbleached sulfate (kraft), bleached and unbleached sulfite, bleached and unbleached soda, neutral sulfite, semi-chemical, chemi-ground wood, ground wood and any combination of these fibers. These designations refer to wood pulp fibers which have been prepared by means of a variety of processes which are known in the pulp and paper industries.

It is understood that all types of additives such as pigments, fillers, stabilizers, retention aids, wet strength additives and dry strength additives, additional sizing agents, and the like may be employed in combination with the copolymer sizing agents of the present invention. Such additaments include kaolin clay, talc, titanium dioxide, calcium carbonate, diatomaceous earth, plastic pigments, aluminum trihydrate, and precipitated silica.

The ammoniated copolymer sizing agents are suit- A sta rch suspension is prepared by stirring 40 g of cationic starch* in 400 g of water at 70C *Potato starch bearing quaternary amino grou s which is sold under the trademark Sta-Lok 400" by ALE. Stanley fg. for 30 minutes. A l-part portion of the aqueous dispersion of copolymer is stirred with ably employed in amounts effective to achieve the pur- 2.7 parts ofthe starch suspension for 5 minutes and diluted by addition h of 338 parts of water. A l-part portion of resulting combined disperposes of the S1Zmg as WaterFeS1Stan9ean sion is added to 236 parts of a 0.33 percent solids aqueous slurry of amount effective t0 S126 the CllulOSlC material. Generbleached sgillfjiltezptalp having a pit-ll of 6.7 ahd prodcessgddin accordance wit AP 0 m- Hands eets are orme an ried in accoramounts rmgmg from i to about dance with TAPPlT-205m-53. Surface wettability by water(anglc of weight percent based on dry weight Of the CBIluiOSlC contact) of the handsheets (precured and cured) is determined and material in the finished sheet or article are suitable, 1O recmded "1 Table With preferred amounts being in the range from about As additional illustration of this embodiment, varying 0.05 to about 2 weight percent and especially preferred amounts of the combfnefi aqueous dlsperslon the amountS being in the range f about 02 to about 7 polymer and the cationic starch are used for internal. weightpercent. It is understood thatwithin this numeri- 511mg of the afofementlofted pulp. In the foregoing cal range, the precise amount which is used will depend manner the treated P p Ffmverted to handsheets f the most part on the type f Cehulosic material and tested for surface wettability. The results are also which is being employed, the specific operating condirecorded In Table tions, as well as the particular end use for which the cellulosic material is destined. For example, paper which TABLE 1 will require good water-resistance or ink holdout will necessitate the use ofa higher concentration or sizing u a i gg i's agent than a paper having characteristics which neces- S l C b/ton 1) PWater (2) i amp 0 oationic resitate the use of only small amounts of sizing. Accord- No potymcr Starch Cured Cured ingly, any amount which is suitable to effect the desired end result of the sizing is suitable for the purpose ofthis l g 3?: invention. 5 9 2? 95 107 These same factors also apply in relation to the 4 ll 5 15 30 102 111 amount of retention aid Wi'll(.i'l is used in COl'lJUllCtlOl] With am moniated copolymer sizing agent. Thus, th (1) Measured in dry weights as pounds o1- specified additive per ton of pulp.

artisan b to use h retention d 3 (2) Surl'ace wcttahility by water (contact angle) before (pro-cured) and/or at'it-r (cured) curing as determined by 'l'AlPl-Jfitlm-JN. the sizing agent in any concentrations which is found to i" ilih. ii-o "'n ci t' 3 bL App] i L t L F fc f' 5 1on7 m (1) Measured in dry weights as pounds of specified tern-ally sizing cellulosic material as defined hercinbeadditive per ton of pulp. fore. However, as a general rule, the retention aid is (2) Surface wettability by water (contact angle) beusually employed in amount in the range from about f ore (pre-cured) and/or after (cured) curing as de- 0.5 to about 8 weight parts per 1 weight part of copolytermined by TAPPI-458m-48. mer sizing agent, preferably from about 1.5 to about 4 wei ht arts of retention aid er I wei ht art of cop g p EXAMPLEZ p0 ymer sizing agent.

. 40 7 The following examples are given to illustrate the I d E 1 l f preferred embodiment of the invention and should not bl n fi g i p h fi un' be construed aslimiting its scope. In these examples, all fi p a f parts and percentages are by weight unless otherwise 5 Own m a e are miema y slzc. Orme m 0 noted handsheets and tested for ink penetration. The results are recorded in Table ll.

EXAMPLE 1 For purposes of comparison, several portions of an A 500-g portion of ethylene/acrylic acid (8 bleached sulfite pulp as described above are internally copolymer a ng a um average mOleCular weight sized using a conventional rosin size as set forth in Of 6950 15 added to 240 ml 0f q ou ammonla Table ll, formed into handsheets and tested for ink pen- Percent a) In a 4 lltef kettle COnIamlrlg 5O etration in a similar manner. The results which are retefs of Water- The foregoing ingredients are surfed corded in Table ll establish the copolymer to be a more 8 hours at and the resulting dispersion 15 effective sizing agent over a wider range ofpH than the lowed to cool to room temperatur T e isper i n is conventional rosin size. The results of ink penetration passed through gauze t0 em flOCCUlaIGd mateflalas recorded in Table II indicates the ability of the sized The resulting filtrate is an aqueous dispersion contain- 55 paper to resist t ti f i k ppli d to one side of ing 13.6 percent ethylene/amm0nlum acryla OP ythe paper to the other. A higher value of percent reflecmer solids and having pH of about 8. tance indicates a higher resistance to penetration.

TABLE ll Size Retention Aid lnk Penetration. Sample Concentration Concentration Beater 7: reflectance at No. Type lb/ton (1) Type lb/ton (1) pH sec. (2)

1 Et/AA(NH )(a) 12 Starch(b) 22 4.5 97 2 Et/AA(NH )(a) 12 Starch(b) 22 6.5 93 3 Et/AA(NH )(a) l2 Starch(b) 22 8.5 83 4 Et/AA(NH -,)(a) 6.4 Starch(b) 12 5.5 81 5 Et/AA(NH )(a) 7 Starch(b) 13 5.5 81 6 Et/AA(NH )(a) 15 Starch(b) 15 5.5 81

% reflectance has a 10071 reflectance.

TABLE llContinued Size Retention Aid lnk Penetration, Sample Concentration Concentration Beater reflectance at No. Type lb/ton (1) Type lb/ton (1) pH 120 sec. (2)

c.* Rosin( c) 40 Alum(dl 80 4.5 75 C Rosin(c) 20 Alum(d) 60 4.5 50 C Rosin(c) Alum(d) 30 4.5 50 Cf Rosin(c) Alum(d) 40 5.75 71 Not an example of the invention.

(a) Ammoniated ethylene/acrylic acid copolymer described in Example 1. (b) Cationic starch.

(c) Maleic anhydride modified rosin.

(d) Aluminum sulfate (paper maker's grade).

(1) Same as in Table 1.

(2) A photometric determination of black ink penetration through white or side of the paper opposite to which a pool of the black ink is applied. The

EXAMPLE 3 in a manner similar to Example 2, bleached kraft pulp is internally sized with the copolymer of Example 1 and a variety of other sizes set forth in Table 111, formed into handsheets and tested for ink penetration. The results which are recorded in Table 111 show that the copolymer is a better sizing agent in terms of resistance to ink penetration under the prescribed conditions than the conventional sizes listed.

EXAMPLE 4 in a manner similar to Example 2, bleached kraft. hardwood pulp is internally sized with a copolymer of 58.5 percent ethylene and 41.5 percent ammonium aclightcolored paper by measuring light reflectance on the paper tested prior to inking using a black background of sheets and dried in accordance with TAPPI T-205m-53 and tested for surface wettability and ink penetration. The results are recorded in Table IV.

For the purposes of comparison, portions of an identical pulp are similarly sized with a copolymer of 54.7 percent ethylene and 45.3 percent sodium acrylate and a copolymer of 47.0 percent ethylene and 53.0 percent potassium acrylate. These comparative treated pulp slurries are formed into handsheets and dried in accordance with TAPPI T-205m-53 and tested for surface wettability and ink penetration. The results which are recorded in Table IV establish that the ammonium salt form of the copolymer is an effective sizing agent rylate. The internally sized pulp is formed into handwhereas alkali metal salt forms are not.

TABLE 111 Size Retention Aid lnk Penetration, Sample Concentration Concentration Beater 7c reflectance at No. Type lb/ton (1) Type lb/ton (1) pH 120 sec. (2)

1 Et/AA(NH )(a) 10.8 Starch(b) 21.6 4.5 93 2 Et/AA(NH.1)(a) 8.6 Starch(b) 17.2 4.5 93 3 ET/AA(NH )(a) 7.0 Starch(b) 14.0 4.5 88 C,* Poly(iminol stearate) 7.0 Starch(b) 14.0 4.5 90 C Poly(iminol stearate) 6.0 Starch(b) 12.0 4.5 86 C Poly(imino1 stearate) 5.2 Starch(b) 10.4 4.5 80 CR Poly(iminol stearate) 4.4 Starch(b) 8.8 4.5 C Rosin(c) 20 Alum(d) 40 4.5 87 C Rosin(c) 15 Alum(d) 30 4.5

Not an example of the invention. (a)-(d) Same as in Table 11. (1H2) Same as in Table 11. I" I TABLE IV Contact Angle Size Retention Aid With Water-(2) lnk Penetration, Sample Concentration Concentration Pre- Reflectance at No. Type(a) lb/ton (1) Type lb/ton (1) cured Cured 120 sec. (3)

1 Et/AA(NH 20 Polyyami- 10 107 116 88% 2 Et/AA(NH 40 Polyami- 10 111 116 99% ne(b) A,* Et/AA(Na) 20 Polyaami- 10 82 100 O A Et/AA(Na) 40 Polygamf 10 98 O B Et/AA(K) 20 Polyami- 10 95 101 O 8 Et/AA(K) 40 Polyami- 10 102 104 58% ne(b) Not an example of the invention.

(a) All sizes prepared from the same ethylene/acrylic acid (653/347) copolymer having a number average molecular weight of 4570.

(h) Polyalkylene polyamine. (1) Same as (l) in Table 11. (2) Same as (2) in Table l. (3) Same as (2) in Table 11.

EXAMPLE A 500-g portion of ethylene/acrylic acid (87.3/12.7) copolymer having a melt flow viscosity [ASTM D- 1238-65T(B) using a plastometer having a 0.020 inch orifice] of 2 decig./min. (having a number average molecular weight of 6,950) is added to 240 mls. of aqueous ammonia (28 percent NH in a 4 liter kettle containing 2.94 liters of water. The foregoing ingredients are stirred for 8 hours at 100C, and the resulting dispersion is allowed to cool to room temperature. The dispersion is passed through gauze to remove floccu lated material. The resulting filtrate is an aqueous dispersion containing 13.6 copolymer solids.

An aqueous solution of a retention aid as specified in Table V is added in proportions specified in Table V to bleached kraft pulp slurry (0.33 percent solids in water) while stirring. The copolymer dispersion is added to the stirred pulp slurry in amount indicated in Table V. The pH of the pulp slurry is adjusted to 4.5 by adding sulfuric acid and the pulp slurry is formed into handsheet. The handsheet is tested for ink penetration and water contact angle and the results are recorded in Table V. g

E AMPLE 9...

A 7.3-lb. portion of ethylene/acrylic acid (86/14) copolymer having a melt flow viscosity (ASTM D-1238- 65T(B) with a 0.020 inch orifice) of 2 decig./min. (number average molecular weight of 4,450) is added to 7.5 gallons of water and 0.617 gallons of aqueous ammonia (28% NH:,) in a 10 gallon rilled kettle. The kettle is heated and stirred for three hours at 100C and psi. The product is drained and filtered through a 100 mesh stainless steel screen. A good amber colored dispersion having 10 percent copolymer solids is obtained.

A 4-part portion of the epichlorohydrin/ammonia reaction product as used in Example 5 (25 percent solids) is diluted with 27 parts of water. A 2.9-part portion of the foregoing copolymer dispersion is diluted with 4.8 parts of water. The two dilutions are added to a bleached kraft pulp slurry. The mixture is adjusted to a pH of 3.5 with sulfuric acid. The pulp slurry is formed into a handsheet and tested for ink penetration and water contact angle. The foregoing procedure is repeated using pulp slurries adjusted to pH values of 4.8, 6.1, 7.1, 7.9, 9.1, and 10.2. The results of the foregoing tests which are recorded in Table VI show the copolymer sizing agent to be effective over a wide range of pH.

EXAMPLE 7 A 40-g portion of ethylene/acrylic acid (89/11) copolymer having a melt flow viscosity (ASTM D1,238- T(B) with a 0.20 inch orifice) of 43 deciglmin. (number average molecular weight of 4075) is added to 27 g. of aqueous ammonia (28 percent of NH- and 200 g. of water in a 0.5 liter stainless steel bomb reactor. The bomb is sealed and the reaction mixture is shaken for 3 hours at C. The resulting dispersion contains 15 percent copolymer solids.

A 0.18-part portion of an epichlorohydrin/ammonia reaction product as used in Example 5 (25 percent solids) is diluted with 6 parts of water. The resulting solution is added to a bleached kraft pulp slurry in the proportion set forth in Table VII and is stirred for one TABLE V Copolymer Retention Aid Ink Penetration, Sample Concentration Concentration Reflectance at No. lb/ton (1) Type lb/ton (1) 120 sec. (2) Contact Angle(3), precured 1 6 PAPA(a) 6 93 95 2 6 NH /EPCH(b) 15 93 103 3 4 NH -,/EPCH(b) 15 70 105 4 l PEl(c) 7.5 83 90 5 2 PEl(c) 7.5 97 6 4 PAECHR(d) 15 90 106 (a) Polyalkylene polyamine flocculant sold under the trademark Purifloc C-3l" by The Dow Chemical Co. (b) Reaction product of epichlorohydrin/ammonia in the mole ratio of 1.7:1, said reaction product having molecular weight peaks at 5000 and 50,000 as measured by gel permeation chromatography. (c) Polyethylenimine having a molecular weight of 600,000. (d) Polyamide epichlorohydrin resin.

(1) Same as In Table l.

(2) Same as in Table 11.

TABLE VI Additive Concentration( 1 lbs/ton Ethylene/Ammoniated Sample Acrylic Acid Ammonia/Epichlorohydrin lnk Penetration,

Copolymer Reaction Product sec. (2) precured pH(4) 1 10 15 98 115 35 2 1O 15 98 120 4.8 3 10 15 99 117 6.1 4 10 15 99 118 7.1 5 l0 15 100 122 7.9 6 l0 15 95 120 9.1 7 10 15 98 118 10.2

(1) Same as in Table l. (2) Same as in Table I1. (3) Same as (3) in Table V.

(4) pH of pulp slurry before processing into hundsheets.

minute. A 0.19-part portion of the foregoing ethylene copolymer dispersion is diluted with 7.7 parts of water and is then added to the pulp slurry as an internal size in the proportion specified in Table VII. The pH of the TABLE VIII Size Retention aid gigs? (tJontcen- B l Contact Ink penera ion, ea er an 10. t Sample N 0. Type lb./ton 1 Type 1b./ton 1 pH dcgreis 2 tioil 1 Et/AA(NH3) 5 NH3/EPCI (I 6.4 117 (1- AK Et/AMNHe 5 NHz/EPCH s) e. 65 e0 0. ti Et/AA(NH3) 10 Sta-10k 400 6. 84 6. 0 B El;/AA(NH3) l0 Sta-10k 400 20 6. 22 20 0.1

Not an example of the invention.

' Ammoniated ethylene/acrylic acid (86/14) copolymer having a number average molecular weight of 4,450.

b Ammoniated ethylene/acrylic acid (80.5/19.a)

copolymer having a number average molecular weight M30000.

Ammoniated ethylene/acrylic acid (80/20) copolymer having a melt flow viscosit ASTM-D138-65 T F 0f 250 deerg/rnln. whlch approximately corresponds to a number average molecularxdeight of 18,300. )1 Reaction product of eplehloroltydrln/ammonla in a mole ratio of 1.61:1, said reaction product having molecular weight peaks at 2,500 and 65,000 as determined by gel permeation chromatography.

9 Potato starch bearing quaternary amine groups as follows:

and manufactured by A. E. Staley Manufacturing.

1 Same as in Table I. 3 Same as (3) in Table V.

3 Time in seconds taken for paper to have an 80% reflectance using test method (2) in Table 11.

resulting pulp slurry is adjusted to 4.5 with sulfuric acid. The pulp is formed into a handsheet and is tested for ink penetration and water contact angle. The results are listed in Table Vll.

TABLE Vll Additive Concentration( l lbs/ton Ammonia/Epichlorohydrin Sample Ethylene Copolymer Reaction Product Ink Penetration, Reflectance at 120 sec. (2)

Contact Angle, precured (3) (1) Same as in Table 1. (2) Same as in Table 11. (3) Same as (3) in Table V.

EXAMPLE 8 Following the procedure of Example 5, an aqueous dispersion (11 percent copolymer solids) of ammoniated ethylene/acrylic acid (86/14) copolymer having a number average molecular weight of 4,450 is prepared.

An aqueous solution of a retention aid as specified in Table Vlll is added in proportions specified in Table lure is followed exceptthat higher molecular weight improvement wherein the internal sizing agent is a water-dispersible, waterand alkali-insoluble copolymer of an a,,B-ethylenically unsaturated hydrophobic monomer and an ammoniated a,B-ethylenica1ly unsaturated carboxylic acid, said copolymer having a number average molecular weight as determined by ebulliometry in the range from about 1,000 to about 10,000.

2. The improvement according to claim 1 wherein the cellulosic material is pulp.

3. The improvement according to claim 1 wherein the hydrophobic monomer is an a,/3-ethylenically unsaturated hydrocarbon.

4. The improvement according to claim 3 wherein the hydrocarbon is an aliphatic a-monoolefin having 2 to 14 carbon atoms.

5. The improvement according to claim 4 wherein the aliphatic a-monoolefin in ethylene.

6. The improvement according to claim 1 wherein the carboxylic acid is acrylic acid.

7. The improvement according to claim 1 wherein the carboxylic acid is methacrylic acid.

8. The improvement according to claim 5 wherein the copolymer is film-forming under the conditions of internal sizing.

9. The improvement of claim 8 wherein the copolymer has a number average molecular weight in the range from about 3000 to about 8000 and contains from about 10 to about weight percent of a,,B-ethylenically unsaturated carboxylic acid.

10. The improvement according to claim 8 wherein the retention aid is the reaction product of ammonia and epihalohydrin.

11. The improvement of claim 10 wherein the reaction product has at least one molecular weight peak as determined by gel permeation chromatography in the range from about 2000 to about 70,000.

12. The improvement according to claim 8 wherein the retention aid is a cationic starch.

13. The improvement according to claim 8 wherein the retention aid is a polyalkylene polyamine.

14. The improvement according to claim 8 wherein the retention aid is polyethyleneimine.

15. The improvement according to claim 8 wherein the retention aid is a polyacrylamide.

16. The improvement according to claim 8 wherein the retention aid is a polyamidepichlorohydrin resin.

17. The improvement according to claim 1 wherein the cellulosic material is internally sized under conditions of pH of at least 7.

18. An internal sizing composition for a cellulosic material comprising a sizing amount of a water dispersible, waterand alkali-insoluble copolymer of an afi-ethylenically unsaturated hydrophobic monomer and an ammoniated a,B-ethylenically unsaturated carboxylic acid, said copolymer containing from about 6 to about 40 weight percent of the ammoniated carboxylic acid and having a number average molecular weight in the range from about 1,000 to about 10,000 and an amount of a retention aid effetive to retain the copolymer on the cellulosic material.

19. The composition according to claim 18 wherein the retention aid is a cationic starch.

20. The composition according to claim 18 wherein the hydrophobic monomer is ethylene and the carboxylic acid is acrylic acid.

21. The composition of claim 18 wherein a reaction product of epihalohydrin and ammonia is the retention aid.

. mg? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 7 ,039 Dated March 18 1975 lnventofls) Walter Lee Vaughn et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

. Cover page, fifth line down under the heading "Abstract", 7

delete the space between the alpha and beta so that it reads --a,B-ethylenically.

Column 2, line 54, the word "of" should be to-.

Q Column 3 line 35, the word "operations" should be -operation--.

Column 3, line 39, the word "dispersion" should be ---dispersions-.

. Column 3, line 61, the word "minimumm" should be minimum.

Column 8, lines 33-37, delete the footnotes (l) & 2),

second occurrence, as they already appear directly under table.

. Column 11, line 14, after the number "13 .6", insert a percent sign so that it reads l3.6%.

Column 11, Table V, the footnote (3) was not indicated beneath the table. This footnote should read as follows:

Q (3) Same as (2) in Table I except that no determination is made subject to curing.

Column 14, line 65, in Claim 5, the word "in" should be -is-.

Q Column 15, line 23, in Claim 14, the word "polyethyleneimine" should be -polyethylenimine--.

Column 16, line 15, in Claim 18, the word "effetive" should be effective.

0 p -Signed and Sacalcd this seventh Day of 0-ct0ber1975 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Altesting Officer Commissioner oflalems and Trademarks 

1. IN A METHOD FOR INTERNAL SIZING OF A CELLULOSIC MATERIAL WHEREIN AN INTERNAL SIZING AGENT AND A RETENTION AID ARE APPLIED TO THE FIBERS OF THE CELLULOSIC MATERIAL, THE IMPROVEMENT WHEREIN THE INTERNAL SIZING AGENT IS A WATER-DISPERSIBLE, WATERAND ALKALI-INSOLUBLE COPOLYMER OF AN A,B-ETHYLENICALLY UNSATURATED HYDROPHOBIC MONOMER AND AN AMMONIATED A,BETHYLENICALLY UNSATURATED CARBOXYLIC ACID, SAID COPOLYMER HAVING A NUMBER AVERAGE MOLECULAR WEIGHT AS DETERMINED BY EBULLIOMETRY IN THE RANGE FROM ABOUT 1,000 TO ABOUT 10,000.
 2. The improvement according to claim 1 wherein the cellulosic material is pulp.
 3. The improvement according to claim 1 wherein the hydrophobic monomer is an Alpha , Beta -ethylenically unsaturated hydrocarbon.
 4. The improvement according to claim 3 wherein the hydrocarbon is an aliphatic Alpha -monoolefin having 2 to 14 carbon atoms.
 5. The improvement according to claim 4 wherein the aliphatic Alpha -monoolefin in ethylene.
 6. The improvement according to claim 1 wherein the carboxylic acid is acrylic acid.
 7. The improvement according to claim 1 wherein the carboxylic acid is methacrylic acid.
 8. The improvement according to claim 5 wherein the copolymer is film-forming under the conditions of internal sizing.
 9. The improvement of claim 8 wherein the copolymer has a number average molecular weight in the range from about 3000 to about 8000 and contains from about 10 to about 20 weight percent of Alpha , Beta -ethylenically unsaturated carboxylic acid.
 10. The improvement according to claim 8 wherein the retention aid is the reaction product of ammonia and epihalohydrin.
 11. The improvement of claim 10 wherein the reaction product has at least one molecular weight peak as determined by gel permeation chromatography in the range from about 2000 to about 70,000.
 12. The improvement according to claim 8 wherein the retention aid is a cationic starch.
 13. The improvement according to claim 8 wherein the retention aid is a polyalkylene polyamine.
 14. The improvement according to claim 8 wherein the retention aid is polyethyleneimine.
 15. The improvement according to claim 8 wherein the retention aid is a polyacRylamide.
 16. The improvement according to claim 8 wherein the retention aid is a polyamidepichlorohydrin resin.
 17. The improvement according to claim 1 wherein the cellulosic material is internally sized under conditions of pH of at least
 7. 18. An internal sizing composition for a cellulosic material comprising a sizing amount of a water-dispersible, water- and alkali-insoluble copolymer of an Alpha , Beta -ethylenically unsaturated hydrophobic monomer and an ammoniated Alpha , Beta -ethylenically unsaturated carboxylic acid, said copolymer containing from about 6 to about 40 weight percent of the ammoniated carboxylic acid and having a number average molecular weight in the range from about 1,000 to about 10,000 and an amount of a retention aid effetive to retain the copolymer on the cellulosic material.
 19. The composition according to claim 18 wherein the retention aid is a cationic starch.
 20. The composition according to claim 18 wherein the hydrophobic monomer is ethylene and the carboxylic acid is acrylic acid.
 21. The composition of claim 18 wherein a reaction product of epihalohydrin and ammonia is the retention aid. 